Funny how seriously Ben takes it considering he was born much later and the only world he knows is the destroyed world. The only normal world to him. I guess they do not have many photos of the normal world?

True enough, he's only known the world like this. But he has seen some (few, rare) surviving photos, so he's at least a little aware.
But he's definitely aware of how much harder things are now, so he can sympathize a bit.

I don't know if it's necessarily an inevitability though for her world... is it? >_> If it is, then it would start to explain how these Walker technologies came about, maybe someone wanted to find a way to stop it from happening somehow and figured out a way to tap across dimensions and alternate realities (like through the walkie-talkie). Ben might just be someone who happens to have the ability to see across dimensions without the aid of technology?